Image (left) from page 217, Frank Leslie's New York Journal, 1855.
Via the Barometer World website, I just ran into "The Tempest Prognosticator" aka the "Leech Barometer". At first glance I assumed it was named after a Mr Leech; but no:
First exhibited by the inventor in 1851 at The Great Exhibition in London. designed in the style of Indian temple architecture, it is a complex and glorious extravaganza to predict storms using leeches.
- Barometer World
The rationale of the device, invented by the Whitby physician George Merryweather MD, was that leeches allegedly become agitated before storms and climb out of the water, and the Tempest Prognosticator comprised a set of vials with attached chains leading to a bell. Supposedly the imprisoned leeches, on the approach of a storm, would disturb the chains and ring the bell. There's no evidence of it working. The original device has been lost, but Whitby Museum has a replica made in 1951 and Barometer World museum in Merton, Devon, has a newer replica on display. Here's a nice Flickr image of the one at Whitby; see also Martin Packer's Victorian Web article Dr. George Merryweather’s 1851 Tempest Prognosticator.
Merryweather's 1851 monograph about the device - An Essay Explanatory of the Tempest Prognosticator in the Building of the Great Exhibition for the Works of Industry of All Nations - is online at the Internet Archive (ID: anessayexplanat00merrgoog) and Google Books. It's a marvellously flakey mix of observations on weather wisdom, Whitby, leeches, animal instinct and atmospheric electricity. A member of the Whitby Literary and Philosophical Society, Merryweather was a correspondent with Michael Faraday and a friend of John Wesley. Nor was it Merryweather's only invention: his others include a "Platina Lamp" and an "apparatus for maintaining a uniform temperature". He was also curator of Whitby Museum. A classic eccentric Victorian polymath, then; the combination of Whitby and leeches would have made him a great bit part in Dracula.